Light-emitting diode and method for manufacturing the same

ABSTRACT

The disclosure provides a light-emitting diode and a method for manufacturing the same. The light-emitting diode comprises a N-type metal electrode, a N-type semiconductor layer contacted with the N-type metal electrode, a P-type semiconductor layer, a light-emitting layer interposed between the N-type semiconductor layer and the P-type semiconductor layer, a low-contact-resistance material layer positioned on the P-type semiconductor layer, a transparent conductive layer covered the low-contact-resistance material layer and the P-type semiconductor layer, and a P-type metal electrode positioned on the transparent conductive layer.

RELATED APPLICATIONS

This application claims priority to Taiwan Application Serial Number102105423 filed Feb. 8, 2013, which is herein incorporated by reference.This application is a divisional of U.S. application Ser. No.14/054,303, filed Oct. 15, 2013, having a common title with the instantapplication and naming Chia-Lin Hsiao as the inventor, which is herebyincorporated by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a light-emitting diode, and moreparticularly, to a light-emitting diode having a low contact resistancelayer.

2. Description of Related Art

A light-emitting diode (LED) is generally formed an epitaxy structure onan insulation substrate, wherein the epitaxy structure includes a P-typemetal electrode, a P-type semiconductor layer, a light-emitting layer,an N-type semiconductor layer, and an N-type metal electrode. In theLED, the insulation substrate may be sapphire. Since it is required forthe P-type metal electrode and the N-type metal electrode of the LED tobe formed on the same surface of the insulation layer, the currentcrowding easily occurs on the surface and decreases the light-emittingefficiency of the LED, so as to degrade the operation potential of theLED.

FIG. 1 is shown a cross-sectional view of a conventional light-emittingdiode (LED) 100. The LED 100 includes a substrate 110, an N-typesemiconductor layer 120, a light-emitting layer 130, a P-typesemiconductor layer 140, a P-type metal electrode 150 and an N-typemetal electrode 160. In FIG. 1, current 170 starts from the P-type metalelectrode 150, and goes through the P-type semiconductor layer 140, thelight-emitting layer 130 and the N-type semiconductor layer 120 to reachthe N-type metal electrode 160. Since the current 170 always goes apathway of the lowest resistance, the current crowding is apt togenerate near the P-type metal electrode 150 or the N-type metalelectrode 160, which decreases the light-emitting efficiency of the LED100. As shown in FIG. 1, the current crowding occurs near the N-typemetal electrode 160.

FIG. 2 is shown a cross-sectional view of a conventional LED 200 and aschematic view of a current pathway in the LED 200. The LED 200 includesa substrate 210, an N-type semiconductor layer 220, a light-emittinglayer 230, a P-type semiconductor layer 240, a transparent conductivelayer 250, a P-type metal electrode 260 and an N-type metal electrode270. In FIG. 2, if the resistance of the transparent conductive layer250 is far less than the resistance of the N-type semiconductor layer220, the current may follow the pathway A, from the P-type metalelectrode 260 to the N-type metal electrode 270, and then the currentcrowding occurs near the N-type metal electrode 270. If the resistanceof the N-type semiconductor layer 220 is far less than the resistance ofthe transparent conductive layer 250, the current may follow the pathwayB, from the P-type metal electrode 260 to the N-type metal electrode270, and then the current crowding occurs near the P-type metalelectrode 260.

Due to the occurrence of the current crowding, the conventional LED hashigher operation potential at the P-type metal electrode or the N-typemetal electrode. And in an LED, such uneven distribution of current maycause uneven distribution in color, premature saturation of lightintensity, and insufficient reliability of electrical elements.Therefore, an improved LED and a method of manufacturing the same areneeded to solve the aforementioned problems.

SUMMARY

The present disclosure provides a light-emitting diode having alow-contact-resistance material layer and a method for manufacturingthereof, so as to solve the problems of the prior art and achieve betterperformance.

One aspect of the present disclosure is to provide a light-emittingdiode (LED). The LED comprises an N-type metal electrode, an N-typesemiconductor layer contacting with the N-type metal electrode, a P-typesemiconductor layer, a light-emitting layer sandwiched between theN-type semiconductor layer and the P-type semiconductor layer, alow-contact-resistance material layer positioned on part of the surfaceof the P-type semiconductor layer, a transparent conductive layercovering the low-contact-resistance material layer and the P-typesemiconductor layer, and a P-type metal electrode positioned on thetransparent conductive layer.

According to one embodiment of the present disclosure, the N-typesemiconductor layer comprises a mesa structure having a first area and asecond area, wherein the first area has a higher level than that of thesecond area, the light-emitting layer and the P-type semiconductor layeris formed on the first area, and the N-type metal electrode ispositioned on the second area of the mesa structure.

According to one embodiment of the present disclosure, the low contactresistance layer surrounds the P-type metal electrode, or is positionedbetween vertical projection regions of the P-type metal electrode andthe N-type metal electrode.

According to one embodiment of the present disclosure, the N-type metalelectrode and the P-type metal electrode are positioned on two oppositesides of the light-emitting layer.

According to one embodiment of the present disclosure, thelow-contact-resistance material layer completely or partially surroundsthe P-type metal electrode.

According to one embodiment of the present disclosure, thelow-contact-resistance material layer is in a round-hole pattern, astripe pattern, a lattice pattern, or a combination thereof.

According to one embodiment of the present disclosure, the material ofthe low-contact-resistance material layer is graphene or a metalselected from the group comprising of nickel (Ni), gold (Au), chromium(Cr), platinum (Pt), rhodium (Rh), titanium (Ti), aluminum (Al), silver(Ag), copper (Cu) and the combinations thereof.

According to one embodiment of the present disclosure, the thickness ofthe low-contact-resistance material layer is in a range of 0.1 nm to1000 nm.

According to one embodiment of the present disclosure, the LED furthercomprises a metal-indium contact layer positioned between the P-typesemiconductor layer and the low-contact-resistance material layer, andthe transparent conductive layer covers the low-contact-resistancematerial layer and the metal-indium contact layer.

According to one embodiment of the present disclosure, the metal-indiumcontact layer is an indium tin oxide (ITO) layer.

Another aspect of the present disclosure is to provide a method formanufacturing the LED. The method for manufacturing the LED comprisesthe following steps. A substrate is provided, and an N-typesemiconductor layer is formed on the substrate, wherein the N-typesemiconductor layer is in a mesa structure having a first area and asecond area, and the first area has a higher level than that of thesecond area. A light-emitting layer is formed on the first area of theN-type semiconductor layer. A P-type semiconductor layer is formed onthe light-emitting layer. A low-contact-resistance material layer isformed on part of the P-type semiconductor layer. A transparentconductive layer is formed on the low-contact-resistance material layerand the P-type semiconductor layer. An N-type metal electrode is formedon the second area of the N-type semiconductor layer, and a P-type metalelectrode is formed on the transparent conductive layer. The LED is in amesa structure, and the P-type metal electrode and the N-type metalelectrode of the LED are on the same side of the substrate.

According to one embodiment of the present disclosure, thelow-contact-resistance material layer surrounds the P-type metalelectrode, or is positioned between vertical projection areas of theP-type metal electrode and the N-type metal electrode.

According to one embodiment of the present disclosure, thelow-contact-resistance material layer is in a round-hole pattern, astripe pattern, a lattice pattern, or a combination thereof.

According to one embodiment of the present disclosure, the material ofthe low-contact-resistance material layer is graphene or a metalselected from the group comprising of nickel (Ni), gold (Au), chromium(Cr), platinum (Pt), rhodium (Rh), titanium (Ti), aluminum (Al), silver(Ag), copper (Cu) and the combinations thereof.

According to one embodiment of the present disclosure, the thickness ofthe low-contact-resistance material layer is in a range of 0.1 nm to1000 nm.

According to one embodiment of the present disclosure, the methodfurther comprises forming a metal-indium contact layer positionedbetween the P-type semiconductor layer and the low-contact-resistancematerial layer, and the transparent conductive layer covers thelow-contact-resistance material layer and the metal-indium contactlayer.

According to one embodiment of the present disclosure, the metal-indiumcontact layer is an indium tin oxide (ITO) layer.

Another aspect of the present disclosure is to provide a method formanufacturing the LED. The method for manufacturing the LED comprisesthe following steps. An N-type semiconductor layer is provided, whichhas a first surface and a second surface opposite to the first surface.A light-emitting layer is formed on the first surface of the N-typesemiconductor layer. A P-type semiconductor layer is formed on thelight-emitting layer. A low-contact-resistance material layer is formedon and surrounds the P-type semiconductor layer. A transparentconductive layer is formed on the low-contact-resistance material layerand the P-type semiconductor layer. A P-type metal electrode is formedon the transparent conductive layer, and an N-type metal electrode isformed on the second surface of the N-type semiconductor layer. The LEDis in a vertical structure, and the P-type metal electrode and theN-type metal electrode of the LED are on the opposite sides of theN-type semiconductor layer.

According to one embodiment of the present disclosure, thelow-contact-resistance material layer completely or partially surroundsthe P-type metal electrode.

According to one embodiment of the present disclosure, thelow-contact-resistance material layer is in a round-hole pattern, astripe pattern, a lattice pattern, or a combination thereof.

According to one embodiment of the present disclosure, the material ofthe low-contact-resistance material layer is graphene or a metalselected from the group comprising of nickel (Ni), gold (Au), chromium(Cr), platinum (Pt), rhodium (Rh), titanium (Ti), aluminum (Al), silver(Ag), copper (Cu) and the combinations thereof.

According to one embodiment of the present disclosure, the thickness ofthe low-contact-resistance material layer is in a range of 0.1 nm to1000 nm.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which;

FIG. 1 is a cross-sectional view of a conventional LED, in which thearrows represent current pathway;

FIG. 2 is a cross-sectional view of a conventional LED, in which thearrows represent current pathway;

FIG. 3A is a cross-sectional view of an LED according to one embodimentof the present disclosure, in which the arrows represent currentpathway;

FIG. 3B is a cross-sectional view of an LED according to one embodimentof the present disclosure, in which the arrows represent currentpathway;

FIG. 4A is a cross-sectional view of an LED according to one embodimentof the present disclosure;

FIG. 4B is a cross-sectional view of an LED according to one embodimentof the present disclosure;

FIG. 4C is a cross-sectional view of an LED according to one embodimentof the present disclosure;

FIG. 4D is a cross-sectional view of an LED according to one embodimentof the present disclosure;

FIG. 5A is a cross-sectional view of an LED according to one embodimentof the present disclosure;

FIG. 5B is a top view of an LED according to one embodiment of thepresent disclosure;

FIGS. 6A-6K and 6M-6P are top views of LEDs according to embodiments ofthe present disclosure;

FIG. 7 is a plurality of patterns of low-contact-resistance materiallayers in LEDs according to embodiments of the present disclosure;

FIGS. 8A-8H are cross-sectional views of manufacturing an LED accordingto one embodiment of the present disclosure; and

FIGS. 9A-9F are cross-sectional views of manufacturing an LED accordingto one embodiment of the present disclosure.

DETAILED DESCRIPTION

The LED and the method for manufacturing the same of the embodiments arediscussed in detail below, but not limited the scope of the presentdisclosure. The same symbols or numbers are used to the same or similarportion in the drawings or the description. And the applications of thepresent disclosure are not limited by the following embodiments andexamples, which the person in the art can apply in the related field.

The singular forms “a” “an” and “the” used herein include pluralreferents unless the context clearly dictates otherwise. Therefore,reference to, for example, a low-contact-resistance material layerincludes embodiments having two or more such low-contact-resistancematerial layers, unless the context clearly indicates otherwise.Reference throughout this specification to “one embodiment” means that aparticular feature, structure, or characteristic described in connectionwith the embodiment is included in at least one embodiment of thepresent disclosure. Therefore, the appearances of the phrases “in oneembodiment” or “in an embodiment” in various places throughout thisspecification are not necessarily all referring to the same embodiment.Further, the particular features, structures, or characteristics may becombined in any suitable manner in one or more embodiments. It should beappreciated that the following figures are not drawn to scale; rather,the figures are intended; rather, these figures are intended forillustration.

In the aforementioned FIG. 2, according to the difference of theresistance between the transparent conductive layer 250 and the N-typesemiconductor layer 220, the current path form the P-type metalelectrode 260 to the N-type current electrode 270 may be roughly classedas path A and path B.

If the resistance of the transparent conductive layer 250 is much lessthan the resistance of the N-type semiconductor layer 220, the currentis followed path A from the P-type metal electrode 260 to the N-typemetal electrode 270, and generate current crowding near the N-type metalelectrode 270. Conversely, if the resistance of the N-type semiconductorlayer 220 is much less than the resistance of the transparent conductivelayer 250, the current is followed path B from the P-type metalelectrode 260 to the N-type metal electrode 270, and generate currentcrowding near the P-type metal electrode 260.

FIG. 3A is a cross-sectional view of an LED 300 a according to oneembodiment of the present disclosure, in which the arrows representcurrent pathway. The LED 300 a comprises a substrate 310, an N-typesemiconductor layer 320, a light-emitting layer 330, a P-typesemiconductor layer 340, a low-contact-resistance material layer 350 a,a transparent conductive layer 360, a P-type metal electrode 370 and anN-type metal electrode 380.

In FIG. 3A, the N-type semiconductor layer 320 is positioned on thesubstrate 310. The N-type semiconductor layer 320 has a first area 321and a second area 322, and the second area 322 is a mesa structure,wherein the first area 321 is higher than the second area 322. Thelight-emitting layer 330 and the P-type semiconductor layer 340 aresequentially formed on the first area 321, and the N-type metalelectrode 380 is positioned on the second area 322. Thelow-contact-resistance material layer 350 a is positioned on part of thesurface of the P-type semiconductor layer 340, and is close to theN-type metal electrode 380. The transparent conductive layer 360 coversthe low-contact-resistance material layer 350 a and the P-typesemiconductor layer 340. The P-type metal electrode 370 is positioned onthe transparent conductive layer 360.

If the resistance of the N-type semiconductor layer 320 is much lessthan the resistance of the transparent conductive layer 360, the currentis followed path B in FIG. 2 from the P-type metal electrode 370 to theN-type metal electrode 380, and generate current crowding near theP-type metal electrode 370. As shown in FIG. 3A, thelow-contact-resistance material layer 350 a is positioned near theN-type metal electrode 380, which may reduce the difference of theresistance between the N-type semiconductor layer 320 and thetransparent conductive layer 360, so that current is uniformlydistributed in the projection region between the P-type metal electrode370 and the N-type metal electrode 380.

According to one embodiment of the present disclosure, an LED 400 afurther comprises a metal-indium-contact layer 410, as shown in FIG. 4A.The metal-indium-contact layer 410 is positioned on the P-typesemiconductor layer 340, and then the transparent conductive layer 360covers the low-contact-resistance material layer 350 a and themetal-indium-contact layer 410. In FIG. 4A, the low-contact-resistancematerial layer 350 a contacts to the P-type semiconductor layer 340.According to one embodiment of the present disclosure, themetal-indium-contact layer 410 is an indium-tin-oxide layer.

According to one embodiment of the present disclosure, an LED 400 cfurther comprises a metal-indium-contact layer 410, as shown in FIG. 4C.The metal-indium-contact layer 410 is sandwiched between the P-typesemiconductor layer 340 and the low-contact-resistance metal layer 350c, and then the transparent conductive layer 360 covers thelow-contact-resistance material layer 350 a and the metal-indium-contactlayer 410. According to one embodiment of the present disclosure, themetal-indium-contact layer 410 is an indium-tin-oxide layer.

FIG. 3B is a cross-sectional view of an LED 300 b according to oneembodiment of the present disclosure, in which the arrows representcurrent pathway. The LED 300 b comprises a substrate 310, an N-typesemiconductor layer 320, a light-emitting layer 330, a P-typesemiconductor layer 340, a low-contact-resistance material layer 350 b,a transparent conductive layer 360, a P-type metal electrode 370 and anN-type metal electrode 380.

In FIG. 3B, the N-type semiconductor layer 320 is positioned on thesubstrate 310. The N-type semiconductor layer 320 has a first area 321and a second area 322, and the second area 322 is a mesa structure,wherein the first area 321 is higher than the second area 322. Thelight-emitting layer 330 and the P-type semiconductor layer 340 issequentially formed on the first area 321, and the N-type metalelectrode 380 is positioned on the second area 322. Thelow-contact-resistance material layer 350 b is positioned on part of thesurface of the P-type semiconductor layer 340, and is close to theP-type metal electrode 370. The transparent conductive layer 360 coversthe low-contact-resistance material layer 350 b and the P-typesemiconductor layer 340. The P-type metal electrode 370 is positioned onthe transparent conductive layer 360.

If the resistance of the transparent conductive layer 360 is much lessthan the resistance of the N-type semiconductor layer 320, the currentis followed path A in FIG. 2 from the P-type metal electrode 370 to theN-type metal electrode 380, and generate current crowding near theN-type metal electrode 380. As shown in FIG. 3B, thelow-contact-resistance material layer 350 b is positioned near theP-type metal electrode 370, which may reduce the difference of theresistance between the N-type semiconductor layer 320 and thetransparent conductive layer 360, so that current is uniformlydistributed in the projection region between the P-type metal electrode370 and the N-type metal electrode 380.

According to one embodiment of the present disclosure, an LED 400 bfurther comprises a metal-indium-contact layer 410, as shown in FIG. 4B.The metal-indium-contact layer 410 is positioned on the P-typesemiconductor layer 340, and then the transparent conductive layer 360covers the low-contact-resistance material layer 350 b and themetal-indium-contact layer 410. In FIG. 4B, the low-contact-resistancematerial layer 350 b contacts to the P-type semiconductor layer 340.According to one embodiment of the present disclosure, themetal-indium-contact layer 410 is an indium-tin-oxide layer.

According to one embodiment of the present disclosure, an LED 400 dfurther comprises a metal-indium-contact layer 410, as shown in FIG. 4D.The metal-indium-contact layer 410 is sandwiched between the P-typesemiconductor layer 340 and the low-contact-resistance metal layer 350d, and then the transparent conductive layer 360 covers thelow-contact-resistance material layer 350 d and the metal-indium-contactlayer 410. According to one embodiment of the present disclosure, themetal-indium-contact layer 410 is an indium-tin-oxide layer.

FIG. 5A is a cross-sectional view of an LED 500 according to oneembodiment of the present disclosure. The LED 500 comprises an N-typemetal electrode 510, an N-type semiconductor layer 520, a light-emittingdiode 530, a P-type semiconductor layer 540, a low-contact-resistancematerial layer 550, a transparent conductive layer 560 and a P-typemetal electrode 570.

In FIG. 5A, the N-type semiconductor layer 520 contacts to the N-typemetal electrode 510. The light-emitting layer 530 is sandwiched betweenthe N-type semiconductor layer 520 and the P-type semiconductor layer540. The low-contact-resistance material layer 550 covers thelow-contact-resistance material layer 550 and the P-type semiconductorlayer 540. In which, the N-type metal electrode 510 and the P-type metalelectrode 570 are individually positioned on the opposite sides of thelight-emitting layer 530.

FIG. 5B is a top view of an LED 500 according to one embodiment of thepresent disclosure. In FIG. 5B, the P-type metal electrode 570 ispositioned on the center of the transparent conductive layer 560, andthen the low-contact-resistance material layer 550 completely around theP-type metal electrode 570. According to one embodiment of the presentdisclosure, the low-contact-resistance material layer is partiallyaround the P-type metal electrode.

FIG. 6A is a top view of an LED 600 a according to embodiments of thepresent disclosure. In FIG. 6A, the LED 600 a comprises an N-type metalelectrode 610 a, an N-type semiconductor layer 620 a, a transparentconductive layer 630 a, a P-type metal electrode 640 a and alow-contact-resistance material layer 650 a. In which, thelow-contact-resistance material layer 650 a is in a stripe pattern,which is parallel arranged on the transparent conductive layer 630 a,and is close to the N-type metal electrode 610 a.

FIG. 6B is a top view of an LED 600 b according to embodiments of thepresent disclosure. In FIG. 6B, the LED 600 b comprises an N-type metalelectrode 610 b, an N-type semiconductor layer 620 b, a transparentconductive layer 630 b, a P-type metal electrode 640 b and alow-contact-resistance material layer 650 b. In which, thelow-contact-resistance material layer 650 b is in a stripe pattern,which is parallel arranged on the transparent conductive layer 630 b,and is close to the N-type metal electrode 610 b.

FIG. 6C is a top view of an LED 600 c according to embodiments of thepresent disclosure. In FIG. 6C, the LED 600 c comprises an N-type metalelectrode 610 c, an N-type semiconductor layer 620 c, a transparentconductive layer 630 c, a P-type metal electrode 640 c and alow-contact-resistance material layer 650 c. In which, thelow-contact-resistance material layer 650 c is in a lattice pattern,which is parallel arranged on the transparent conductive layer 630 c,and is close to the N-type metal electrode 610 c.

FIG. 6D is a top view of an LED 600 d according to embodiments of thepresent disclosure. In FIG. 6D, the LED 600 d comprises an N-type metalelectrode 610 d, an N-type semiconductor layer 620 d, a transparentconductive layer 630 d, a P-type metal electrode 640 d and alow-contact-resistance material layer 650 d. In which, thelow-contact-resistance material layer 650 d is in a lattice pattern,which is parallel arranged on the transparent conductive layer 630 d,and is close to the N-type metal electrode 610 d.

FIG. 6E is a top view of an LED 600 e according to embodiments of thepresent disclosure. In FIG. 6E, the LED 600 e comprises an N-type metalelectrode 610 e, an N-type semiconductor layer 620 e, a transparentconductive layer 630 e, a P-type metal electrode 640 e and alow-contact-resistance material layer 650 e. In which, thelow-contact-resistance material layer 650 e is in a stripe pattern,which is parallel arranged on the transparent conductive layer 630 e,and is close to the N-type metal electrode 610 e. It is worthwhile tonote that, the more close to the N-type metal electrode 610 e, the wideris the width of the low-contact-resistance material layer 650 e.

FIG. 6F is a top view of an LED 600 f according to embodiments of thepresent disclosure. In FIG. 6F, the LED 600 f comprises an N-type metalelectrode 610 f, an N-type semiconductor layer 620 f, a transparentconductive layer 630 f, a P-type metal electrode 640 f and alow-contact-resistance material layer 650 f. In which, thelow-contact-resistance material layer 650 f is in a stripe pattern,which is parallel arranged on the transparent conductive layer 630 f,and is close to the N-type metal electrode 610 f. It is worthwhile tonote that, the more close to the N-type metal electrode 610 f, the wideris the width of the low-contact-resistance material layer 650 f.

FIG. 6G is a top view of an LED 600 g according to embodiments of thepresent disclosure. In FIG. 6G, the LED 600 g comprises an N-type metalelectrode 610 g, an N-type semiconductor layer 620 g, a transparentconductive layer 630 g, a P-type metal electrode 640 g and alow-contact-resistance material layer 650 g. In which, thelow-contact-resistance material layer 650 g is in a stripe pattern,which is parallel arranged on the transparent conductive layer 630 g,and is close to the N-type metal electrode 610 g. It is worthwhile tonote that, the more close to the N-type metal electrode 610 g, theshorter is the distance of the low-contact-resistance material layer 650g.

FIG. 6H is a top view of an LED 600 h according to embodiments of thepresent disclosure. In FIG. 6H, the LED 600 h comprises an N-type metalelectrode 610 h, an N-type semiconductor layer 620 h, a transparentconductive layer 630 h, a P-type metal electrode 640 h and alow-contact-resistance material layer 650 h. In which, thelow-contact-resistance material layer 650 h is in a stripe pattern,which is parallel arranged on the transparent conductive layer 630 h,and is close to the N-type metal electrode 610 h. It is worthwhile tonote that, the more close to the N-type metal electrode 610 h, theshorter is the distance of the low-contact-resistance material layer 650h.

FIG. 6I is a top view of an LED 600 i according to embodiments of thepresent disclosure. In FIG. 6I, the LED 600 i comprises an N-type metalelectrode 610 i, an N-type semiconductor layer 620 i, a transparentconductive layer 630 i, a P-type metal electrode 640 i and alow-contact-resistance material layer 650 i. In which, thelow-contact-resistance material layer 650 i is in a square shape, andcompletely surrounds the P-type metal electrode 640 i.

FIG. 6J is a top view of an LED 600 j according to embodiments of thepresent disclosure. In FIG. 6J, the LED 600 j comprises an N-type metalelectrode 610 j, an N-type semiconductor layer 620 j, a transparentconductive layer 630 j, a P-type metal electrode 640 j and alow-contact-resistance material layer 650 j. In which, thelow-contact-resistance material layer 650 i is in a multiple frame, andcompletely surrounds the P-type metal electrode 640 j.

FIG. 6K is a top view of an LED 600 k according to embodiments of thepresent disclosure. In FIG. 6K, the LED 600 k comprises an N-type metalelectrode 610 k, an N-type semiconductor layer 620 k, a transparentconductive layer 630 k, a P-type metal electrode 640 k and alow-contact-resistance material layer 650 k. In which, thelow-contact-resistance material layer 650 k is in a lattice frame, andcompletely surrounds the P-type metal electrode 640 k.

FIG. 6M is a top view of an LED 600 m according to embodiments of thepresent disclosure. In FIG. 6M, the LED 600 m comprises an N-type metalelectrode 610 m, an N-type semiconductor layer 620 m, a transparentconductive layer 630 m, a P-type metal electrode 640 m and alow-contact-resistance material layer 650 m. In which, thelow-contact-resistance material layer 650 m is in a U-shape, andpartially surrounds the P-type metal electrode 640 m, and the opening ofthe U-shape is toward the N-type metal electrode 610 m.

FIG. 6N is a top view of an LED 600 n according to embodiments of thepresent disclosure. In FIG. 6N, the LED 600 n comprises an N-type metalelectrode 610 n, an N-type semiconductor layer 620 n, a transparentconductive layer 630 n, a P-type metal electrode 640 n and alow-contact-resistance material layer 650 n. In which, thelow-contact-resistance material layer 650 n has a plurality of roundholes, which is parallel arranged on the transparent conductive layer630 n, and is close to the N-type metal electrode 610 n.

FIG. 6O is a top view of an LED 600 o according to embodiments of thepresent disclosure. In FIG. 6O, the LED 600 o comprises an N-type metalelectrode 610 o, an N-type semiconductor layer 6200, a transparentconductive layer 630 o, a P-type metal electrode 640 o and alow-contact-resistance material layer 650 o. In which, thelow-contact-resistance material layer 650 o has a plurality of roundholes, which is parallel arranged on the transparent conductive layer630 o, and is close to the N-type metal electrode 610 o.

FIG. 6P is a top view of an LED 600 p according to embodiments of thepresent disclosure. In FIG. 6P, the LED 600 p comprises an N-type metalelectrode 610 p, an N-type semiconductor layer 620 p, a transparentconductive layer 630 p, a P-type metal electrode 640 p and alow-contact-resistance material layer 650 p. In which, thelow-contact-resistance material layer 650 p is in a frame with aplurality of round holes, and completely surrounds the P-type metalelectrode 640 p.

According to one embodiment of the present disclosure, the material ofthe low-contact-resistance material layer is graphene or a metalselected from the group comprising of nickel (Ni), gold (Au), chromium(Cr), platinum (Pt), rhodium (Rh), titanium (Ti), aluminum (Al), silver(Ag), copper (Cu) and the combinations thereof.

According to one embodiment of the present disclosure, the thickness ofthe low-contact-resistance material layer is in a range of 0.1 nm to1000 nm.

According to one embodiment of the present disclosure, thelow-contact-resistance material layer comprises a plurality of patterns700 a-700 e as shown in FIG. 7.

FIGS. 8A-8H are cross-sectional views of manufacturing an LED 800according to one embodiment of the present disclosure. In FIG. 8A, asubstrate 810 is provided. And then, an N-type semiconductor layer 820is formed on the substrate 810, as shown in FIG. 8B, wherein the N-typesemiconductor layer 820 has a first area 821 and a second area 822. InFIG. 8C, a light-emitting layer 830 is formed on the N-typesemiconductor layer 820. In FIG. 8D, a P-type semiconductor layer 840 isformed on the light-emitting layer 830.

In FIG. 8E, by an etching step, the P-type semiconductor layer 840, thelight-emitting layer 830 and part of the N-type semiconductor layer 820positioned on the second area 822 of the N-type semiconductor layer 820are removed, so that the first area 821 of the N-type semiconductorlayer 820 is higher than the second area 822. And then, alow-contact-resistance material layer 850 is formed on part of theP-type semiconductor layer 840, as shown in FIG. 8F. A transparentconductive layer 860 is formed on the low-contact-resistance materiallayer 850 and the P-type semiconductor layer 840, as shown in FIG. 8G.In FIG. 8H, a P-type metal electrode 870 is formed on the transparentconductive layer 860, and an N-type metal electrode 880 is formed on thesecond area 822 of the N-type semiconductor layer 820, so as to form theLED 800. In which, the LED 800 has a mesa structure, and the P-typemetal electrode 870 and the N-type metal electrode 880 are positioned atthe same side of the substrate 810.

According to one embodiment of the present disclosure, the low contactresistance layer 850 surrounds the P-type metal electrode 870, or ispositioned between vertical projection regions of the P-type metalelectrode 870 and the N-type metal electrode 880.

According to one embodiment of the present disclosure, thelow-contact-resistance material layer 850 is in a round-hole pattern, astripe pattern, a lattice pattern, or a combination thereof.

According to one embodiment of the present disclosure, the material ofthe low-contact-resistance material layer 850 is graphene or a metalselected from the group comprising of nickel (Ni), gold (Au), chromium(Cr), platinum (Pt), rhodium (Rh), titanium (Ti), aluminum (Al), silver(Ag), copper (Cu) and the combinations thereof.

According to one embodiment of the present disclosure, the thickness ofthe low-contact-resistance material layer 850 is in a range of 0.1 nm to1000 nm.

According to one embodiment of the present disclosure, the LED furthercomprises a metal-indium-contact layer sandwiched between the P-typesemiconductor layer and the low-contact-resistance metal layer, and thenthe transparent conductive layer covers the low-contact-resistancematerial layer and the metal-indium-contact layer. According to oneembodiment of the present disclosure, the metal-indium-contact layer isan indium-tin-oxide layer.

FIGS. 9A-9F are cross-sectional views of manufacturing an LED accordingto one embodiment of the present disclosure. In FIG. 9A, an N-typesemiconductor layer 910 is provided, and has a first surface 911 and asecond surface 912 on the opposite side. A light-emitting layer 920 isformed on the first surface 911 of the N-type semiconductor layer 910,as shown in FIG. 9B. And then, in FIG. 9C, a P-type semiconductor layer930 is formed on the light-emitting layer 920.

In FIG. 9D, a low-contact-resistance material layer 940 is formed aroundthe P-type semiconductor layer 930. And then, a transparent conductivelayer 950 is formed on the low-contact-resistance layer 940 and theP-type semiconductor layer 930, as shown in FIG. 9E. In FIG. 9F, aP-type metal electrode 960 is formed on the transparent conductive layer950, and an N-type metal electrode 970 is formed on the second surface912 of the N-type semiconductor layer 910, so as to form the LED 900. Inwhich, the LED 900 has a vertical structure, and the P-type metalelectrode 960 and the N-type semiconductor layer 970 are on the oppositesides of the N-type semiconductor layer 910.

According to one embodiment of the present disclosure, thelow-contact-resistance material layer 940 surrounds the P-type metalelectrode 960 completely or partially.

According to one embodiment of the present disclosure, thelow-contact-resistance material layer is in a round-hole pattern, astripe pattern, a lattice pattern, or a combination thereof.

According to one embodiment of the present disclosure, the material ofthe low-contact-resistance material layer graphene or a metal isselected from the group comprising of nickel (Ni), gold (Au), chromium(Cr), platinum (Pt), rhodium (Rh), titanium (Ti), aluminum (Al), silver(Ag), copper (Cu) and the combinations thereof.

According to one embodiment of the present disclosure, the thickness ofthe low-contact-resistance material layer is in a range of 0.1 nm to1000 nm.

Although embodiments of the present disclosure and their advantages havebeen described in detail, they are not used to limit the presentdisclosure. It should be understood that various changes, substitutionsand alterations can be made herein without departing from the spirit andscope of the present disclosure. Therefore, the protecting scope of thepresent disclosure should be defined as the following claims,

What is claimed is:
 1. A method for manufacturing a light-emittingdiode, comprising: providing a substrate; forming an N-typesemiconductor layer on the substrate, wherein the N-type semiconductorlayer is in a mesa structure having a first area and a second area, andthe first area is higher than the second area; forming a light-emittinglayer on the first area of the N-type semiconductor layer; forming aP-type semiconductor layer on the light-emitting layer; forming alow-contact-resistance material layer on part of the P-typesemiconductor layer; forming a transparent conductive layer on thelow-contact-resistance material layer and the P-type semiconductorlayer; and forming individually an N-type metal electrode on the secondarea of the N-type semiconductor layer, and a P-type metal electrode onthe transparent conductive layer.
 2. The method of claim 1, wherein thelow-contact-resistance material layer surrounds the P-type metalelectrode, or is positioned between vertical projection areas of theP-type metal electrode and the N-type metal electrode.
 3. The method ofclaim 1, wherein the low-contact-resistance material layer is in around-hole pattern, a stripe pattern, a lattice pattern, or acombination thereof.
 4. The method of claim 1, wherein the material ofthe low-contact-resistance material layer is graphene or a metalselected from the group comprising of nickel (Ni), gold (Au), chromium(Cr), platinum (Pt), rhodium (Rh), titanium (Ti), aluminum (AD, silver(Ag), copper (Cu) and the combinations thereof.
 5. The method of claim1, wherein the thickness of the low-contact-resistance material layer isin a range of 0.1 nm to 1000 nm.
 6. The method of claim 1, furthercomprising forming a metal-indium contact layer positioned between theP-type semiconductor layer and the low-contact-resistance materiallayer, and the transparent conductive layer covers thelow-contact-resistance material layer and the metal-indium contactlayer.
 7. The method of claim 6, wherein the metal-indium contact layeris an indium tin oxide (ITO) layer.
 8. A method for manufacturing alight-emitting diode, comprising: providing an N-type semiconductorlayer having a first surface and a second surface opposite to the firstsurface; forming a light-emitting layer on the first surface of theN-type semiconductor layer; forming a P-type semiconductor layer on thelight-emitting layer; forming a low-contact-resistance material layersurrounding the P-type semiconductor layer; forming a transparentconductive layer on the low-contact-resistance material layer and theP-type semiconductor layer; and forming individually a P-type metalelectrode on the transparent conductive layer, and an N-type metalelectrode on the second surface of the N-type semiconductor layer. 9.The method of claim 8, wherein the low-contact-resistance material layercompletely or partially surrounds the P-type metal electrode.
 10. Themethod of claim 8, wherein the low-contact-resistance material layer isin a round-hole pattern, a stripe pattern, a lattice pattern, or acombination thereof.
 11. The method of claim 8, wherein the material ofthe low-contact-resistance material layer is graphene or a metalselected from the group comprising of nickel (Ni), gold (Au), chromium(Cr), platinum (Pt), rhodium (Rh), titanium (Ti), aluminum (Al), silver(Ag), copper (Cu) and the combinations thereof.
 12. The method of claim8, wherein the thickness of the low-contact-resistance material layer isin a range of 0.1 nm to 1000 nm.